1. Field
Embodiments of the present invention relate to a liquid crystal display device and a fabrication method of the same, and more specifically, embodiments of the present invention relate to a medium and small-sized liquid crystal display device to display images, having a size smaller than a typical laptop computer, and a fabrication method of the medium and small-sized liquid crystal display device.
2. Description of the Related Technology
A liquid crystal display device controls light transmittance of a liquid crystal by using an electric field, thereby displaying images. The liquid crystal display device controls a field between a pixel electrode and a common electrode, which are disposed facing each other, one on a lower substrate on which a thin film transistor is formed and the other on an upper substrate on which a color filter is formed, thereby driving the liquid crystal.
In general, a liquid crystal display device includes a lower substrate and an upper substrate, which are bonded to one another, and face each other, a spacer to uniformly maintain a cell gap between the lower substrate and the upper substrate, and a liquid crystal filled in the cell gap.
The upper substrate is generally configured to include a color filter to implement colors, a black matrix to prevent light leakage, a common electrode to control an electric field, and an alignment layer coated to align the liquid crystal. The lower substrate is generally configured to include a plurality of signal wires and a thin film transistor, a pixel electrode connected to the thin film transistor, and an alignment layer coated to align the liquid crystal. In addition, the lower substrate includes a storage capacitor to stably maintain a pixel voltage in the pixel electrode.
The storage capacitor is typically formed by forming a lower electrode and an upper electrode, and an insulating layer therebetween. The storage capacitor is generally required to have a large capacitance, in order to be applied to a high resolution display while maintaining the pixel voltage signal stable. However, in order to increase the capacitance of the storage capacitor, the area of overlap between the upper and lower electrodes of the storage capacitor generally needs to be widened. The area occupied by the upper and lower electrodes contributes to degrading the aperture ratio.
Among the operation modes of liquid crystal display devices, the PVA (Patterned Vertical Alignment) mode can improve the viewing angle of the liquid crystal display devices by arranging the liquid crystal particles in different directions to form a liquid crystal domain, using a patterned transparent electrode. This necessitates a process for forming the patterned transparent electrode to manufacture a liquid crystal display device operable in the PVA mode.
Another way to implement the PVA mode is by forming protrusions on an opposite substrate, and a common electrode on the substrate with the protrusions, to form a liquid crystal domain. In such devices an independent process of forming the protrusions is necessitated.
The process of patterning the transparent electrode and/or the process of forming protrusions while forming the liquid crystal domain of a liquid crystal display device increase the number of manufacturing processes. Further, misalignment between the display substrate and the opposite substrate during assembly contributes to misalignment of the patterns of the pixel electrodes of the display substrate and the common electrodes of the opposite substrate, thereby complicating the formation of the liquid crystal domain. Patterning the transparent electrode and forming the protrusions also decrease the aperture ratio of the liquid crystal display device.